Liquid urethane compositions for textile coatings

ABSTRACT

Disclosed is a polyurethane based composition for treating textiles to provide such treated textile with oil, water or oil and water repellency. The composition comprises a polyfunctional liquid polyurethane-containing adduct wherein the adduct contains as a first functional group at least one structo-terminal blocked isocyanate moiety per molecule, and at least one second structo-terminal functional group per molecule which is a perfluoro or siloxane moiety.

This application claims the benefit of 60/060,298 filed Sep. 29, 1997.

The present invention relates to textile treatment compositions toimpart oil and water repellency to textiles, methods of treatingtextiles and to the resulting treated textiles.

Various processes exist for the treatment of textiles to impart somewater and/or oil repellency. For example, the use of variousfluorochemical compositions for such purposes on fibers and fibroussubstrates, is known. See, for example, Banks, Ed., OrganofluorineChemicals and Their Industrial Applications, Ellis Horwood Ltd.,Chichester, England, 1979, pp. 226-234. As the fluorochemicals aregenerally expensive, extenders are generally added to reduce the cost.Considerable effort has been put forth in finding suitable extenders foruse with fluorochemicals to impart water and oil repellency to fibers.

U.S. Pat. No. 5,466,770 describes a fluorochemical oil- andwater-repelling agent together with a polymer extender and a polymerextender having a saturated carbon-carbon backbone chain and at leastone percent by weight, based on the weight of the extender, ofinterpolymerized units derived from ethylenically-unsaturated monomercontaining at least one blocked or masked isocyanato group.

U.S. Pat. No. 3,849,521 (Kirimoto et al.) describes water- andoil-repellent compositions containing an oil- and water-repellentfluoroalkyl-containing polymer and an additive copolymer containingmonomer units having the formula CR₁R₂═CR₃COOR₄, wherein R₁, R₂ and R₃represent hydrogen atoms or methyl groups, and R₄ represents a C₁₋₁₈alkyl group; and monomer units having the formula CH₂═CR₅CONHCH₂OH,wherein R₅ represents a hydrogen atom or a methyl group.

U.S. Pat. No. 4,834,764 (Deiner et al.) describes the use of certainblocked isocyanate compounds in combination with reactive perfluoroalkylcontaining (co)polymers. Such compounds are said to improve the oil andwater repellency and also make possible a reduction in the amount offluoroalkyl-containing compounds.

World patent publication W092/17636 (Dams et al.) describes certaincompositions comprising a fluorochemical agent, a copolymer extender,and a blocked isocyanate extender.

The present invention provides for a tailored reactive molecule suitablefor a chemically bonded thin textile coating that provides water and oilrepellency without significantly impacting the feel of the fabric.

In a first aspect, this invention relates to a liquid polyurethane-basedcomposition which comprises a polyfunctional liquidpolyurethane-containing adduct wherein the adduct contains as a firstfunctional group at least one structo-terminal blocked isocyanate moietyper molecule, and at least one second structo-terminal functional groupper molecule which is a repellent moiety, preferably a perfluoro orsiloxane moiety, or a combination thereof.

In a second aspect, this invention relates to a process for preparing apolyfunctional liquid polyurethane-containing composition as mentionedabove, by a solvent-free multi-step process which comprises reacting ina first step a polyisocyanate with a polyol to provide anisocyanate-terminated intermediate, in a second step reacting theisocyanate-terminated intermediate with a blocking agent to block atleast one isocyanate moiety and in a subsequent step, reacting at leastone isocyanate moiety with a repellent compound. In a preferred methodfor the preparation of the polyfunctional polyurethane:

a) the polyisocyanate comprises at least two isocyanate moieties permolecule with mutually different reactivities to the polyol;

b) the polyol is an organic substance having a molecular weight of from60 to 20,000 and containing per molecule from two or moreisocyanate-reactive functional groups selected from the group consistingof —OH, —SH, —COOH, —NHR where R is hydrogen or alkyl, or epoxy; and

c) the repellent compound is a molecule containing oneisocyanate-reactive functional group selected from the group consistingof —OH, —SH, —COOH, —NHR where R is hydrogen or alkyl, or epoxy andfurther containing a second functional group which is not an isocyanateor an isocyanate-reactive moiety,

characterized in that:

i) the first step is conducted in essentially anhydrous conditions andin the absence of a urethane-promoting catalyst, the polyol is added ata controlled rate to the polyisocyanate such that the reactiontemperature does not exceed 100° C. and the total amount of polyol addedis less than a stoichiometric equivalent with respect to thepolyisocyanate;

ii) for the second step, the blocking agent is added in a total amountof less than a stoichiometric equivalent with respect to the isocyanatecontent of the intermediate;

iii) and in one or more subsequent steps, a repellent compound is addedsuch that the final polymer is substantially free of any isocyanatefunctionality or any isocyanate-reactive functionality.

In another aspect, the invention is to a process for preparation of apolyfunctional polyurethane as above where steps (ii) and (iii) arereversed. Thus in step (ii), a repellent compound is added at less thana stoichiometric equivalent with respect to the isocyanate content ofthe intermediate and in step (iii), the blocking agent is added.

In yet another aspect, this invention relates to a process for impartingwater and oil repellent properties to a textile comprising applying to asurface of a textile an amount of the above disclosed compositionsufficient to impart water and/or oil repellent properties thereto. Suchtreated fibers are preferably heated in a second step at a temperatureand for a time sufficient to cure the treated substrate.

This invention also relates to a repellant textile resulting from thetreatment of such textile by the above described method.

Treatment of fibers by the composition and method of the presentinvention is advantageous in that the fiber retains the touch, feeling,color shade and softness originally possessed by the fibers even aftertreatment and imparts a water and/or oil repellency to such fibers.

A further advantage of the compositions of the present invention fortreating textiles is that the urethane compositions haveself-emulsifyable behavior and due to the nature of the compounds, theirarchitecture can be tailored to result in smaller r emulsion particles.This imparts the advantage of applying a thinner coating of the abovecomposition versus conventional water repellency compounds.

An additional advantage of the present invention is when the repellentmoiety is a perfluoropolyether, such compounds allow self-organizationto take place at room temperature so that the textile does not need toundergo a heat treatment after washing.

The polyfunctional polyurethanes of the present invention provide anadditional advantage in that when applied to a textile, they arechemically bonded to the textile so that the water and/or oil repellencyof such treated textiles is maintained by the textile after repeatedwashings or extensive use.

When used herein, the term “textile” refers to both textiles which arecomposed of natural fibers and/or synthetic fibers, for example wool,cotton, silk, nylon, cellulose and also blends of natural fibers andsynthetic fibers, including synthetic fibers modified to react with anisocyanate functionality. The treated textile may be in the form of afiber, a yarn, a woven fabric, a carpet, a knitted fabric, a nonwovenfabric which are formed from the fibers.

The term “repellent moiety” or “repellent compound”, or variationsthereof, means a moiety or compound which when added to a textile willgive the textile the characteristics of repelling water, oil or oil andwater. Preferred repellent moieties are perfluorocarbons and siloxanes.Perfluorocarbons are generally characterized in imparting to a textilethe ability to repel water and oil and siloxanes are characterized inimparting to a textile the ability to repel water. The ability to repeloils is also associated with stain resistance.

The composition of this invention is characterized in that it comprisesa polyfunctional liquid polyurethane adduct bearing a blocked isocyanatefunctional group and a second different functional group which is arepellent moiety. By the term “liquid” it is meant that the adduct is aliquid at a temperature of 50° C. or less, and preferably is a liquid ata temperature of from 0° C. to 50° C. The composition advantageouslycomprises the adduct in an amount of from 1 to 99, preferably from 5 to95, more preferably from 10 to 90, and yet more preferably from 50 to 90weight percent, based on total parts by weight of the composition.

The polyfunctional liquid polyurethane-containing adduct has a polyolcore which is chain extended with an isocyanate moiety and terminatedwith at least two functional groups. These functional groups arestructo-terminal, that is, they are not pendent. At least one chain endbears a blocked isocyanate functional group, and at least one chain endbears a repellent functional group. In a preferred embodiment of thisinvention, the adduct has on average of from 2 to 8, more preferablyfrom 3 to 8, and yet more preferably from greater than 3 to 6 chain endsper molecule, wherein each chain contains one or more urethane linkages.When the adduct contains from 2 to 8 chain ends per molecule; then from1 to 7 blocked isocyanate moieties per molecule and from 7 to 1perfluoro functional moieties are present. The optimum ratio of maskedisocyanate moiety to second functional moiety will depend on theintended fabric to be treated and can vary within the ranges of from 1:7to 7:1, and preferably from 1:2 to 2:1.

The polyfunctional liquid polyurethanes of the present invention cancontain additional functional moieties such as an aryl, alkyl, ester,nitrile, alkene, alkyne, halogen, silyl or combinations thereof. Theequivalents of repellent moieties, blocking agent and optionallyadditional functional groups is such that the polyfunctionalpolyurethane is substantially free of any isocyanate functionality orany isocyante-reactive functionality.

In general, repellent compounds useful in this invention include any ofthe known agents useful for the treatment of textiles to obtain oil,water or oil and water repellency. Preferred repellent compounds are theknown fluoro-containing and siloxane-containing compounds useful for thetreating of textiles to obtain water and/or oil repellency.

The fluoro-compounds, called R_(f)X for brevity, are stable, inert,non-polar, and both oleophobic and hydrophobic. X refers to aisocyanate-reactive functional group where such functional groupsinclude —OH, —SH, —COOH, —NHR, with R being hydrogen or an alkyl moiety,or epoxy. The R_(f) group preferably contains at least 3 carbon atoms,more preferably 3 to 20 carbon atoms, and most preferably 6 to 14 carbonatoms. R_(f) can contain straight chain, branched chain, or cyclicaliphatic fluorinated groups, aromatic fluorinated groups orcombinations thereof. R_(f) can optionally contain heteroatoms such asoxygen, divalent or hexavalent sulfur, or nitrogen. It is preferred thatR_(f) contains oxygen. It is preferred that R_(f) contains 40 percent to80 percent fluorine by weight, more preferably 50 percent to 78 percentfluorine by weight. The terminal portion of the R_(f) group is fullyfluorinated preferably containing at least 7 fluorine atoms, forexample, CF₃CF₂CF₂—, (CF₃)₂CF—, —CF₂SF₅, F(CF(CF₃)CF₂—O)₄CF(CF₃)CH₂—.Perfluorinated aliphatic groups and perfluorinated ethers are the mostpreferred embodiments of R_(f)X.

Examples of useful fluorochemical agents include, for example, R_(f)containing urethanes, ureas, esters, amines (and salts thereof), amides,acids (and salts thereof), carbodiimides, guanidines, allophanates,biurets, oxazolidinones, and other substances containing one or moreR_(f) groups, as well as mixtures and blends thereof. Such agents arewell known to those skilled in the art, see for example, Kirk-Othmer,Encyclopedia of Chemical Technology, 3rd Ed., Vol. 24, pp. 448-451 andmany are commercially available as ready-made formulations. Usefulfluorochemical agents can be polymers containing multiple R_(f) groupssuch as copolymers of fluorochemical acrylate and/or methacrylate.

Preferred siloxane compounds useful in the present invention can berepresented by the general formula

X—(CH₂)_(n)—O—[(SiO)(CH₃)₂]_(m)—CH₃

where

X is as previously defined;

n is an integer from 1 to 20; and

m is an integer from 1 to 12.

Preferably m is an integer from 2 to 15, and more preferably from 3-12.Preferably n is an integer from 1 to 10, and more preferably from 2 to8. M and n are generally selected such that the molecular weight of thesiloxane compound is 120 to 423,000.

Siloxane compound are commercially available, as from ABCR GmbH & Co.,Karlsruhe, Germany.

The polyisocyanate used in the process to prepare the adduct product hasat least two isocyanate moieties per molecule and which, with respect tothe isocyanate-reactive group of the polyol, are distinguished by adifference in reactivity. The reactivity difference optimizes themanufacture of a product having a narrow molecular weight distributionand reduces the potential for formation of higher oligomers leading togel-like or non-liquid products. When the polyisocyanate contains threeor more isocyanate groups per molecule then the relative reactivity ofthe individual isocyanate moieties is such to minimize formation ofhigher oligomers. Suitable polyisocyanates can be aliphatic orpreferably aromatic polyisocyanates and especially aromatic or aliphaticdiisocyanates. An advantage to using diisocyanates, where the relativereactivity of the individual isocyanate groups are different, is that itpermits the amounts of free, non-reacted, polyisocyanate that may bepresent in the isocyanate-terminated intermediate to be limited to thesubsequent advantage of material requirements for the second processstep, and further to the value of the adduct in end applications.Exemplary of suitable aromatic polyisocyanates include toluenediisocyanate, methylene diphenylisocyanate and polymethylenepolyphenylisocyanates. Exemplary of suitable aliphatic polyisocyanatesinclude isophorone diisocyanate, isopropylcyclohexyl diisocyanate andmethylene dicyclohexylisocyanate. Preferred are polyisocyanatescomprising isomers of toluene diisocyanate, of methylenediphenylisocyanate or mixtures thereof. Especially preferred, forreasons of relative isocyanate reactivity, is 2,4′-methylenediphenylisocyanate and notably 2,4-toluene diisocyanate, or mixturescomprising such diisocyanate.

The term polyol as used herein refers to a compound which has two ormore isocyanate-reactive functional groups per molecule where suchfunctional groups include —OH, —SH, —COOH, —NHR, with R being hydrogenor an alkyl moiety, or epoxy. Preferred is a polyol bearing —OHfunctionality. The polyol may contain up to 8 such functional groups permolecule, preferably from 2 to 8, more preferably from 3 to 8, and mostpreferably from greater than 3 to 6, functional groups per molecule.

The polyol used in the process of this invention has a molecular weightof from 60 to 20,000; preferably from 200, more preferably from 1000,and yet more preferably from 2000; and preferably up to 15,000, and morepreferably up to 10,000. In a preferred embodiment the polyol is apolyester or particularly a polyoxyalkylene polyol where the oxyalkyleneentity comprises oxyethylene, oxypropylene, oxybutylene or mixtures oftwo or more thereof, including especially oxypropylene-oxyethylenemixtures. Alternative polyols that may be used in the invention includepolyalkylene carbonate-based polyols and polyphosphate based polyols.The nature of the polyol selected depends on whether or not to impartsome water solubility to the adduct, which can be advantageous forcertain applications and disadvantageous for other applications. Watersolubility can be enhanced by selection of polyols having a lowermolecular weight or an elevated oxyethylene content.

Suitable polyoxyalkylene polyols are exemplified by various commerciallyavailable polyols as used in polyurethane, lubricant, surfactancyapplications and include polyoxypropylene glycols designated as VORANOL™P-2000 and P-4000 with respectively molecular weights of 2000 and 4000;polyoxypropylene-oxyethylene glycols such as DOWFAX™ DM-30 understood tohave a molecular weight of 600 and an oxyethylene content of 65 weightpercent, and SYNALOX™ 25D-700 understood to have a molecular weight of5500 and an oxyethylene content of 65 weight percent, all available fromThe Dow Chemical Company; polyoxyethylene triols available under thetrademark TERRALOX™ and designated as product WG-98 and WG-116understood to have a molecular weight of 700 and 980, respectively,polyoxypropylene-oxyethylene triols designated as VORANOL™ CP 1000 andCP 3055 understood to have respectively a molecular weight of 1000 and3000, and VORANOL™ CP 3001 understood to have a molecular weight of 3000and an oxyethylene content of 10 weight percent and VORANOL™ CP 6001understood to have a molecular weight of 6000 and an oxyethylene contentof 15 weight percent, all available from The Dow Chemical Company;polyoxypropylene hexols including VORANOL™ RN-482 understood to have amolecular weight of 700, and polyoxyethylene hexols including TERRALOX™HP-400 understood to have a molecular weight of 975, both available fromThe Dow Chemical Company; higher functionality polyether polyolsincluding those based on carbohydrate initiators such as, for example,sucrose and exemplified by VORANOL™ 370 available from The Dow ChemicalCompany.

The blocking group is a conventional blocking agent which is removablefrom the isocyanate under thermal conditions, such as those employedduring cure of a fibrous substrate treated with a compound containingthe blocked isocyanate group.

Conventional isocyanate blocking agents include alcohols such as1,6-hexanediol, ethylene glycol, methanol, ethanol, n-propyl alcohol,isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, t-butyl alcohol,n-amyl alcohol, t-amyl alcohol, 2-ethylhexanol, glycidol; aryl alcohols(for example, phenols, cresols, nitrophenols, o- and p-chlorophenol,naphthols, 4-hydroxybiphenyl); C₂ to C₈ alkanone oximes (for example,acetone oxime, butanone oxime); benzophenone oxime; aryl-thiols (forexample, thiophenol); organic carbanion active hydrogen compounds (forexample, diethyl malonate, acetylacetone, ethyl acetoacetate, ethylcyanoacetate); epsilon-caprolactam; a primary or secondary amine (forexample, butyl amine); hydroxylamine; and primary amino mercaptan andsecondary amino mercaptans. Particularly preferred blocked isocyanatesinclude those blocked with C₂ to C₈ alkanone oximes, for example,2-butanone oxime, with a phenol, with a lactam, with 2-ethylhexanol, orwith glycidol.

In a preferred embodiment of this invention the polyisocyanate istoluene diisocyanate comprising, substantially, the 2,4-isomer; thepolyol is a polyoxyalkylene polyol, especially apolyoxyethylene-oxypropylene polyol containing from 3 to 6 hydroxylgroups; the blocking agent is 2-butanone oxime and the preferredfluorocarbons are CF₃CF₂CF₂—, (CF₃)₂CF—, —CF₂SF₅, andF(CF(CF₃)CF₂—O)₄CF(CF₃)CH₂—.

The method of preparing the polyurethane compositions of the presentinvention comprises a multi-step process.

The first step concerns the preparation of an isocyanate-terminatedintermediate by reacting the polyisocyanate with the polyol at areaction temperature that does not exceed 100° C., in essentiallyanhydrous conditions. By “essentially anhydrous conditions” it is meantthat water is present in an amount of less than 1500, preferably lessthan 750, more preferably less than 350 ppm of total polyisocyanate andpolyol reactants. The presence of water in an amount greater than thisincreases the risk of forming gel or solid products. The reactiontemperature advantageously is from 20° C., more preferably from 35° C.;and preferably up to 80° C., more preferably up to 70° C. At higherreaction temperatures, the beneficial effect of the relative isocyanatereactivity rates can be substantially diminished, and additionallyisocyanate may be consumed by an undesirable allophanate reaction. Thepolyol is added at a controlled rate to the polyisocyanate such that thereaction temperature does not exceed 100° C., and the total amount ofpolyol added is a stoichiometric equivalent or less with respect to thepolyisocyanate. The total amount of polyol advantageously does notexceed 0.99, preferably does not exceed 0.95 of an equivalent; andadvantageously is at least 0.1, preferably at least 0.25, and morepreferably from 0.5 of an equivalent per equivalent of isocyanate.

The first process step is conducted in the absence of a processing aid.By the term “processing aid” in the context of this invention, it ismeant substances that promote the formation of urethane linkage byreaction of isocyanate with an active hydrogen atom. To minimizepotential gel formation, solidification, it is advantageous to usepolyols that do not contain any catalyst or catalyst finishing residues,for example, potassium acetate, which might promote urethane formationor isocyanate dimerization or trimerization. Additionally to minimizegel formation when preparing the intermediate it is advantageous to usepolyols, especially polyols, that have an acid content.

The intermediate can be characterized in that it has an isocyanatecontent of from about 0.5 to about 5, preferably from about 1 to about 4weight percent and is a composition which comprises structures (I),(II), and (III) represented by the structural formulae:

P (-A)_(b)  (I)

A or A-  (II)

A-(P-A)_(c)-P-A  (III)

wherein:

c≧1

A- is a residue from a polyisocyanate;

A is a free polyisocyanate

P is a residue from a polyol; and

b is the number of isocyanate reactive groups formally present on thepolyol.

The proportions and amounts of (I), (II), and (III) based on total moleamount of said substances, in an amount of from: for (I), at least 65,preferably at least 75, more preferably at least 80, and up to 100 molepercent; for (II), less than 35, preferably less than 25, morepreferably less than 15, and most preferably 0 mole percent; and for(III), less than 12, preferably less than about 10, more preferably lessthan about 7, yet more preferably less than 5, and most preferably 0mole percent. In a preferred embodiment the adduct composition maycomprises substances (I), (II), and (III) in the mole percent ranges offrom 65 to 90: from 30 to 5: from about 6 to 1 respectively, wherein thetotal is to 100. By reference to purity, it is understood that the endproduct has a low content of free polyisocyanates and adductsrepresented by structures (II) and (III), respectively.

The proportion and amounts of (I), (II) and (III) are carried over inthe formation of adducts of the present invention. By way of example,when all the isocyanate moieties of the intermediate contain a blockinggroup or repellent group, the final adduct can be represented by thegeneral structure (IV)

(W-A)_((b-d))-P-(A-M)_(d)  (IV)

where

P, A and b are as previously defined;

M represents a blocking moiety;

W represents a repellent moiety; and

d is the number of blocked isocyanate groups.

As per the description herein, b is greater than d.

The process minimizes the formation of structure (III) type substances,resulting in an adduct which has a liquid characteristic at roomtemperature, especially when the polyol used in the preparation of theadduct formally contained three or more isocyanate reactivegroups/molecule. Adduct III is depicted with a linear structure althoughit can have a highly complex branched structure.

When the resulting isocyanate-terminated intermediate has a high free,unreacted, isocyanate content, and before proceeding with the secondstep of the process it can be advantageous to reduce such content by,for example, distillation or extraction techniques using suitablesolvents including pentane or hexane. Free, unreacted isocyanate canparticipate in the second process step providing capped products, thepresence of which in the final product may be detrimental to performancein certain end applications.

In the second step of the process, the isocyanate-terminatedintermediate is reacted with less than a stoichiometric amount of ablocking agent. The stoichiometry is such to provide for the desiredcontent of capped isocyanate moieties.

The process for blocking isocyanates can be carried out under conditionswhich are well know in the art. See for example, U.S. Pat. Nos.,4,008,247; 4,189,601; 4,190,582; 4,191,843; and 4,191,833, thedisclosures of which are incorporated herein by reference, and Z. W.Wicks, Progress in Organic Coatings, volume 3, pages 73-99 (1975) andvolume 9, pages 3-28 (1981). The process temperature is chosen forconvenience of reaction time and can be greater than 80° C. withoutnoticeable detriment to the quality of the resulting product. Exposureto a temperature greater than 100° C. should be minimized to avoidundesirable side reactions, such as reversal of the blocking reaction.

In a third or subsequent step of the process, the partially blockedisocyanate-terminated intermediate is reacted with a repellent compound.When the repellent compound is the final functional moiety to be addedto a partially blocked isocyanate-terminated intermediate, the repellentcompound is added in an amount sufficient to “cap” the remainingreactive isocyanate groups to provide for the final adduct.

For addition of a functional group to the blocked isocyanate-terminatedintermediate, such as a repellent compound, the process temperature ischosen for convenience of reaction time and can be greater than 80° C.In general, exposure to a temperature greater than 100° C. should beminimized for the purpose of avoiding undesirable side reactions. Thereaction of the blocked isocyanate-terminated intermediate with apolyfunctional substance can, if desired, be accelerated by use of asuitable urethane-promoting catalyst. Representative of such catalystsinclude tertiary amine compounds and organotin compounds as used whenpreparing, for example, polyurethane foam by reaction of apolyisocyanate with a polyol. It is to be noted that use of a catalystin this step can lead to final adducts having a higher viscosity thanthose prepared in the absence of catalyst.

A third or subsequent step means at least one step in which a repellentcompound is reacted with a partially blocked isocyanate-terminatedintermediate. Thus the third step encompasses a process where onerepellent compound, such as a fluorocarbon, is added in less than astoichiometric amount with respect to the reactive isocyanate groups,and in a subsequent step another functional moiety is added. Thus theprocess encompasses the addition of multiple repellent molecules orother functional moieties.

The polyurethane compositions of the present invention can also beproduced whereby the final step in the process is the addition of ablocking agent. Thus the isocyanate-terminated intermediate produced inthe first step is reacted with one or more repellent compounds, andoptionally with other functional moieties, in less than a stoichiometricamount with respect to the reactive isocyanate groups. In the final stepsufficient blocking agent is then added to provide a polyfunctionalpolymer which contains substantially no free isocyanate functionality.

The polyfunctional polyurethanes of the present invention can be appliedto the textile by common processes known to those skilled in the art.The polyfunctional polyurethane is generally applied using a solvent.Preferred solvents are ketones, ethers and esters or mixtures thereof.Alternatively, a composition can be prepared in the form of an aqueousdispersion or emulsion and the textile treated therewith. Thepolyfunctional polyurethanes of the present invention are particularadvantageous when containing a perfluoroether in that these are capableof forming an emulsion in water. When water is used as a solvent, wateris preferably present is an amount of 70 to 900 parts by weight based on100 parts of weight of the composition of the invention.

A composition of the invention comprises the polyfunctionalpolyurethane, containing the repellent-functionality, in an amountsufficient to impart repellent properties to a fibrous substrate treatedwith the composition. The amount of the polyfunctional polyurethane thatconstitutes an effective amount can be easily determined to thoseskilled in the art and depends on the particular fluorocarbon agent usedand textile to be treated.

When the composition of the invention is applied as a treatment to afibrous substrate, such as a fabric intended for use in a garment, it ispreferred that the treated substrate comprise the polyfunctionalpolyurethane in a amount of 0.01 percent to 5 percent by weight based onthe weight of the untreated fiber. More preferred is an amount of 0.01percent to 3 percent by weight of the untreated fiber.

Once the polyfunctional polyurethane has been applied to a textile, thetextile is cured at a temperature and for a time sufficient to provide acured treated substrate. This curing process can be carried out attemperatures between 110° C. and 190° C. depending on the particularcomposition used. In general, a temperature of 150° C. for a period of 1to 10 minutes, preferably 3 to 5 minutes, is suitable. The curingprocess breaks the bond between an isocyanate functional group and theblocking agent and allows the isocyanate to react and form a chemicalbond with the treated textile. The cured treated substrate can be cooledto room temperature and used as desired, for example, incorporated orfashioned into a garment such as rainwear.

The need for a blocking agent on an isocyante moiety is to prevent themoiety from reacting with water if the composition is to be applied to afiber in a solvent containing water. In another aspect of the invention,if it is desired to apply a polyurethane composition containing arepellent moiety without the use of a water solvent, the process step ofadding a blocking agent to an isocyanate moiety can be omitted. Thiswill then result in a polyfunctional liquid polyurethane-containingadduct wherein the adduct contains as a first functional group at leastisocyanate moiety per molecule, and at least one second functional groupper molecule which is a repellent moiety. Such compositions can then beapplied to the fibers directly without the need of an aqueous solvent.

The invention is illustrated by the following examples in which allparts and percentages are by weight, unless otherwise stated.

EXAMPLE 1

To a flask fitted with a mechanical stirrer was added 348.32 g oftoluene diisocyanate (TDI) (2.0 mol) and the TDI heated up to 50° C.under a nitrogen atmosphere. To this was slowly added, under vigorousstirring, 500 g of a hexol (0.0833 mol). The final TDI/OH ratio was 4/1.No catalyst was used during the formation of the prepolymer. Totaladdition time was 12 hours. After the addition the reaction mixture wasleft stirring overnight at 50 deg C. The reaction mixtures was thenpassed through a distillation unit to remove excess TDI.

To the above obtained product 14.52 g (0.167 mol) of 2-butanone oximewas quickly added under vigorous stirring. This was followed by theaddition of 0.47 grams (0.05 weight percent based on the total weight ofthe reaction mixture) dibutyltin dilaurate. Next 121.36 g (0.333 mol)1H,1H,2H,2H-perfluorooctan-1-ol was added. The reaction mixture was leftstirring for two hours at 50° C. to complete the reaction. Via thisprocess, on average, four of the six end groups (isocyanate moiety) arecapped with a perfluoro group, and the remaining two end groups arecapped with 2-butanon oxime (blocked isocyanate groups).

To test the oil and water repellency, contact angle experiments havebeen performed on regenerated cellulose foil (Rayophane 600 p), coatedby the polyfunctional polyurethane.

Rayophane 600 p (from UCB Films), which was chemically identical tocotton fiber, was coated by spin casting (10 sec, 3000 rpm) of a 5 wtpercent solution in tetrahydrofuran (THF) to obtain a thin and uniformlayer of the above product. Prior to contact angle measurement, thecellulose foil was annealed for 30 min at 150° C. in vacuum. The contactangle was measured by the sessile drop method. This method was based onmeasuring directly the contact angle of a liquid drop sitting on a flatsurface. Water and hexadecane were chosen for contact angle testing.Water was chosen to measure the water repellency and hexadecane tomeasure the oil repellency (since it has a surface tension similar tooil).

With water, a contact angle of 111.6 deg was measured and withhexadecane a contact angle of 74.81 deg was measured, equalingfluorocarbon surfaces in general.

Also the Water-Repellency Spray Test (AATCC test method 22-1989) and theOil Repellency Test (AATCC test method 118-1992) showed the water andoil repellent properties with values of 100 (water repellency) and 5(oil repellency).

Other embodiments of the invention will be apparent to those skilled inthe art from a consideration of this specification or practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with the true scope and spiritof the invention being indicated by the following claims.

What is claimed is:
 1. A polyfunctional liquid polyurethane-containingadduct wherein the adduct contains as a first functional group at leastone structo-terminal blocked isocyanate moiety per molecule and as asecond structo-terminal functional group at least one siloxane moiety.2. A liquid polyurethane-based composition wherein the compositioncomprises 1 to 99 percent by weight of the adduct of claim
 1. 3. Thecomposition of claim 2 wherein the composition comprises 5 to 95 percentby weight of the adduct of claim
 1. 4. The composition of claim 3wherein the composition comprises 10 to 90 percent by weight of theadduct of claim
 1. 5. The composition of claim 2 wherein the adduct has3 to 8 structo-terminal ends per molecule and 2 to 7 of suchstrutco-terminal ends comprise a siloxane moiety.
 6. A method forimparting water or oil repellent properties to a fibrous substrate,comprising applying to the surface of the fibrous substrate an adduct ofclaim
 1. 7. The method of claim 6 wherein after application of theadduct to the fibrous substrate, the fibrous substrate is heated at atemperature and for a time sufficient to cure the treated substrate. 8.The method of claim 6 wherein the adduct is present on the fibersubstrate in an amount of 0.01 percent to 5 percent by weight based onthe weight of the untreated substrate material.
 9. A textile which istreated with the method according to claim 6.